World's first warm-blooded fish found

New York: Researchers have discovered a first fully warm-blooded fish that circulates heated blood throughout its body much like mammals and birds. The silvery fish, roughly the size of a large automobile tire, is known from oceans around the world and dwells hundreds of feet beneath the surface in chilly, dimly lit waters.

The warm-blooded opah or moonfish swims by rapidly flapping its large, red pectoral fins like wings through the water, giving it a competitive advantage in the cold ocean depths, reported the team from National Oceanic and Atmospheric Administration's National Marine Fisheries (NOAA Fisheries).

"That warm-blooded advantage turns the opah into a high-performance predator that swims faster, reacts more quickly and sees more sharply," said fisheries biologist Nicholas Wegner, lead author of the paper."It turns out to be a very active predator that chases down agile prey like squid and can migrate long distances," he added.

While looking at opah, Wegner recognised an unusual design: Blood vessels that carry warm blood into the fish's gills wind around those carrying cold blood back to the body core after absorbing oxygen from water.